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Isolation and characterization of a azoxystrobin-degrading bacterial strain Ochrobactrum anthropi SH14

Shaohua Chen;Yinyue Deng;Fei He;Lianhui Zhang

  Continuous use of the strobilurin fungicide azoxystrobin(AZX) has resulted in serious environmental contamination problems.We report here that a novel bacterial strain SH14,which was isolated from wastewater treatment system using an enrichment culture technique,was able to degrade and utilize AZX as the carbon and nitrogen source in minimal medium.Based on the morphology,physio-biochemical characteristics,16 S rDNA gene analysis,and API 20 NE systems,strain SH14 was identified as Ochrobactrum anthropi.Strain SH14 degraded 86.3%of 50 mgL~(-1) AZX within 5 days.The optimum conditions for AZX degradation were determined to be30.2℃,pH 7.9 and inocula amount 0.2 g dry wtL~(-1) using response surface methodology.Andrews equation was used to describe the special degradation rate at different initial concentrations.It was observed that strain SH14 degraded AZX up to a concentration of 400 μgmL~(-1) with a maximum specific degradation rate(q_(max)),half-saturation constant(K_s) and inhibition constant(K_i) of 0.612 2 d~(-1),6.829 1 μgmL~(-1)and 188.468 0 μgmL~(-1),respectively.The critical inhibitor concentration was estimated to be 35.875 7 μgmL~(-1).Moreover,strain SH14 participated in efficient degradation of a wide range of strobilurin fungicides including kresoxim-methyl,pyraclostrobin,and trifloxystrobin,which similar to AZX are also widely used pesticides with environmental contamination problems with the degradation process following the first-order kinetic model.Our results highlight the promising potentials of strain SH14 in bioremediation of AZX-contaminated environments.……